1. Field of the Invention
The present invention relates to an optical sensor and a method of manufacturing the same.
2. Description of the Related Art
Conventionally, there has been known an optical sensor including an optical element for detecting ambient brightness, which is used for dimming control in a television set or a mobile device monitor or for other purposes (see, for example, Japanese Patent Application Laid-open Nos. 2006-284474 and 2005-252041). In a photosensor (optical sensor) described in Japanese Patent Application Laid-open No. 2006-284474, a semiconductor chip (optical element) is accommodated in a package or is fixed onto a mounting board and covered by a transparent resin, and the semiconductor chip is connected to leads provided on the mounting board by bonding wires.
In a photoelectric conversion device described in Japanese Patent Application Laid-open No. 2005-252041, using flip-chip bonding (FCB), a light transmissive interposer on which a photoelectric conversion element is mounted and a mounting board are disposed to be opposed to each other at a predetermined gap, and the interposer and the mounting board are supported by solder bumps. Then, external terminals of the interposer connected to electrodes of the photoelectric conversion element are electrically connected to electrodes of the mounting board by the solder bumps. In this manner, the photoelectric conversion element is mounted on the mounting board via the interposer.
However, in the photosensor described in Japanese Patent Application Laid-open No. 2006-284474, the bonding wires extend around the semiconductor chip, and hence it is necessary to increase the size of the external shape of the package or the transparent resin in accordance with the size of the bonding wires. Thus, there is a problem that it is difficult to achieve downsizing and thinning.
On the other hand, as exemplified in the photoelectric conversion device described in Japanese Patent Application Laid-open No. 2005-252041, if the interposer and the mounting substrate are supported by the solder bumps, the postures of the interposer and the mounting board become unstable depending on the shape of the solidified solder bumps. If the interposer is tilted, the optical characteristics may be deteriorated. Depending on the amount of the solder bump, the photoelectric conversion element may contact with the mounting board, and there is another problem that the reliability is lowered. In addition, the photoelectric conversion element is not protected by a package or a resin, and hence the reliability may be deteriorated. In this case, it is conceivable to seal a resin between the interposer and the mounting board, but the sealed resin lowers the light transmission characteristics, and further it is very difficult to seal a resin so as to avoid a photoelectric conversion portion of the photoelectric conversion element. Besides, the resin may be colored with time to change the optical characteristics or moisture may permeate the resin to cause corrosion. Thus, there is a problem that the reliability is insufficient.